(9) 4"x4"x24" pieces, 18 lin.ft. CornerFills are sections of flat-cut Studiofoam corner acoustic absorbers that are beneficial in two ways. Aesthetically, they give you smooth, clean edges against which to butt ythe acoustic wall treatments and acoustic foam bass traps for a more professional appearance. Acoustically, they smooth out the excess low frequency energy that congregates in room corners. CornerFill Cubes are a terrific way to finish out trihedral corners where three LENRD Bass Traps come together. Great for gyms and larger rooms.